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Define the term coordination/sensitivity
This refers to the ability of an organism to detect and respond to stimuli in the environment.
What are the two systems of coordination in animals?
The nervous and endocrine system
What makes up the nervous system?
This is made up of highly specialized cells (neurones), which transmit electrical impulses to and from the brain.
What are receptors?
These are modified nerve cells that receive stimuli from the environment. Examples include the receptor cells in the eyes stimulated by light and the receptor cells in the skin stimulated by touch
What are effectors?
These are cells or organs that carry out an action. Examples include the pupil of the eye dilating when light is shone at it and the sweat glands of the skin which produce sweat in high temperatures
What are the ways in which impulses are transmitted in the nervous system?
They are transmitted electronically and chemically.
What are the types of neurones?
Sensory neurones
Relay/intermediate neurones
Motor neurones
What is the function of the Sensory neurone?
This transmits impulses from the receptors (sense organs) to the CNS along a short axon to the cell body. The dendrite is much longer than the axon, with the dendrites directly touching the receptor cells.
Where is the relay/intermediate neurones located?
This is located in the central nervous system
What is the function of the relay neurone?
This forms a linkage between the Sensory and motor neurones.
Describe the structure of the relay neurone.
It has short dendrites and axons with a cell body
What is the function of the motor neurone?
This transmits impulses from the central nervous system to the effector.
Describe the structure of the motor neurone.
It has a cell body located at one end to which the dendrites and axons are attached.
What are the parts of a neurone?
The dendron
The dendrites
The cell body
The axon
The axon terminal
What are dendrons?
These are nerve fibres that transmit nerve impulses towards the cell body.
OR
This refers to the entire branching structure that extends from a neuron's cell body and transmits nerve impulses
What are dendrites?
These are the end branches of dendrons that carry nerve impulses from other neurones towards the cell body
OR
These are short-branched extensions of a nerve cell, along which impulses received from other cells at synapsis are transmitted to the cell body.
What is the cell body?
This is the structure that contains the nucleus and the cell organelles along with several projections, e.g. dendrites and axons.
What is an axon?
This is a long projection covered by a white fatty material which transmits impulses away from the cell body.
What is the myelin sheath?
This is a white fatty material which covers the axon.
What is the function of the myelin sheath?
This protects the axon from damage and the crossing over of electrical impulses
What is the node of ranvier?
This refers to the gaps between the tightly packed cells of the myelin sheath.
What are axon terminals (nerve endings)?
These refer to the endings of an axon, which carries nerve cells very close to target cells, forming a synapse.
What is a synapse?
This is the junction between two nerve cells (neuron) ends.
How are nerve impulses/messages transmitted across a synapse?
When messages in the form of electrical impulses reach the end of one neuron, they cannot cross the synapse. Therefore, they are converted into a chemical signal by a chemical called a neurotransmitter, such as acetylcholine.
Where is the synapse located?
This is located at the end of an axon of one neurone and the dendrites or cell body of the other neurone.
What are the types of nervous systems?
The Central (CNS)
The Peripheral (PNS)
The Autonomic (ANS)
What is the function of the central nervous system?
This gathers all information from all the body's receptors, which then respond and send messages to the effectors.
What makes up the central nervous system?
This is made up of the brain and the spinal cord
What is the brain?
This is a complex organ that controls thought, memory, emotion, touch, motor skills, vision, breathing, temperature, hunger and every process that regulates our body.
Where is the brain located?
This is located in the head and is protected by the cranium, meninges and cerebrospinal fluid.
What is the function of the cerebrospinal fluid?
This supplies the neurones in the brain with respiratory gases and nutrients and removes waste.
What are the types of matter present in the brain?
White matter which is present on the inside, and grey matter which is present on the outside.
What is the function of the brain?
This performs complex mental and physical activities which bring about the appropriate response.
What are the parts of the brain?
The cerebrum
The cerebellum
The medulla oblongata
What is the cerebrum?
This is the largest part of the brain, which is highly convoluted ( a lot of coils or folds) and forms two hemispheres.
What is the function of the cerebrum?
This receives sensory information from receptors and controls voluntary actions, conscious thoughts, memory, language and personality.
What are the parts/sections of the cerebrum?
The frontal, parietal, temporal and occipital lobes.
What is the function of the frontal lobe?
This is responsible for thinking, memory, movements and behaviour
What is the function of the temporal lobe?
This is responsible for hearing, learning and emotions
What is the function of the parietal lobe?
This is responsible for language and touch
What is the function of the occipital lobe?
This is responsible for sight
What Is the cerebellum?
This is the area of the brain that is associated with the control of muscular movement, posture and balance.
What is the function of the cerebellum( a.k.a gyroscope)?
This receives information from the muscles and tendons and information from the organ of balance in the ear.
Why is the cerebellum referred to as the “gyroscope “ of the body?
This is because it is associated with balance.
What is the medulla oblongata?
This is the part of the brain that is associated with the autonomic nervous system and involves involuntary actions such as breathing, heart beat, peristalsis and blood pressure.
What connects the brain to the spinal cord?
The medulla oblongata
What is the hypothalamus?
This is a small organ in the lower brain which integrates the activities of the nervous and endocrine systems.
What information does the hypothalamic receive?
This receives information about the conditions inside the body and the external environment.
What system is the hypothalamus involved in?
The automatic system and in homeostasis. It is also considered an endocrine gland.
Where is the spinal cord located?
This is located in the back of mammals, is attached to the medulla oblongata, and is protected by the vertebral column/spine/backbone
What are the types of matter present in the spinal cord?
Grey matter which is present on the inside and white matter on the outside.
What is the responsibility of the spinal cord?
This is responsible for reflex actions in mammals.
What is the function of the spinal cord?
It acts as a relay centre between the brain, peripheral sense organs and the peripheral effectors.
What is the function of the peripheral nervous system?
This forms a vast communication network which links the reception of a stimulus to a response.
What makes up the peripheral nervous system?
This is made of nerves, which are composed of bundles of nerve fibres that branch off from the spinal cord, extending to all parts of the body.
What are the types of neurones that are present in nerves?
Motor and sensory neurones or both.
What are the 2 types of nerves within the peripheral nervous system?
The cranial and spinal nerves.
What are the cranial nerves?
This refers to the 12 pairs of nerves that are connected to the brain and supply receptors and effectors to it.
What is the vargus nerve?
This is the longest cranial nerve which contains both sensory and motor nerves.
Where does the vargus nerve pass through?
This passes through the neck and thorax to the abdomen and supplies the heart, lungs and upper digestive tract.
What are the spinal nerves?
This refers to the 31 pairs of spinal nerves, which are laterally connected to the spinal cord and supply effectors and receptors to the rest of the body.
What is the autonomic nervous system?
This is a part of the peripheral nervous system which controls the involuntary actions of smooth muscles and glands.
What is the function of the autonomic nervous system?
This controls the stability of the body’s internal environmental.
What is a reflex action?
This is a rapid, automatic, involuntary response to a stimulus by a muscle or gland, such as the automatic withdrawal of a hand when it touches a hot surface. This reaction occurs without conscious thought.
What are the types of reflexes?
Cranial and spinal reflexes
What are cranial reflexes?
These are impulses that pass through the brain. E.g. salivation, blinking, sneezing, coughing and the response of the pupil to light.
OR
These are reflexes that occur in the head region E.g. salivation, blinking, Sneezing, coughing and the response of the pupil to light.
What are spinal reflexes?
These are reflexes that pass through the spinal cord and do not go to the brain. Examples include the knee jerk and stretch response. They originate in the spine.
What is a reflex arc?
This refers to the nervous pathway between a receptor and an effector.
OR
This refers to the nervous pathway taken by nerve impulses in a reflex action.
Which neurones are involved in simple reflex actions in humans?
The sensory and motor neurons.
What is the function of sense organs?
These detect stimuli in the environment to which a response is initiated.
What do sense organs contain?
These contain receptor cells which receive stimuli and pass it along the nerve cells to the CNS
What are the receptors in the skin?
Pain, cold, heat and pressure receptors
What are the receptors in the tongue and what are their functions?
These are the taste buds which detect chemicals dissolved in moisture in the tongue. The types of taste buds are sour, sweet, salty and bitter.
What is the nerve present in the eye?
The optic nerve
What is the nerve present in the ear?
The auditory/cochlear nerve
What is the nerve present in the nose?
The olfactory nerve
What is the eye?
This is a light sensitive organ that enables us to see small variations of colour, shape, size, brightness and distance.
What are the parts of the eye?
The ciliary body
The conjunctiva
The cornea
The aqueous humour
The lens
The pupil
The iris
The suspensory ligament
The ciliary muscle
The blind spot
The optic nerve
The retina
The fovea
The choroid
The sclera
The vitreous humour
What is the conjunctiva and state is function
This is a thin transparent skin/layer continuous with the lining of the eyelids. It protects the cornea
What is the iris and state its function
This is a coloured disc composed of muscle. It controls the amount of light entering the eye.
What is the aqueous humour and State its function
This is a colorless fluid. It maintains the shape of the cornea
What is the cornea and state its function
This is the transparent front part of the sclera. It refracts (bends) light rays onto the retina
What is the pupil and state its function
This is a hole in the center of the iris. It allows light to enter the eyeball
What is the lens and state its function
This is a transparent, elastic, biconvex structure. It makes fine adjustments to focus light on the retina.
What is the function of the suspensary ligament?
This attaches the lens to the ciliary body
What is the function of the ciliary muscle and state its function
This is a circular ring of muscle that runs through the ciliary body. It alters the shape of the lens during accommodation
What is accommodation?
This is the process by which the lens adjust for focusing on near and distant objects
What is the function of the optic nerve?
This carries impulses from the retina to the brain
What is the blind spot?
This is the point where the optic nerve leaves the eye; no light sensitive cells are present.
Why is the blind spot called the ‘blind spot’?
This is because it lacks photoreceptors and is insensitive light whereas light falling in that area does not cause a response in the nerve, so you are ‘blind’ at that point
What is the retina?
This is the part of the eye that contains light sensitive cells called rods and cones. It is the part where images are formed.
What are the photoreceptors in the eye?
The rods and cones which are present in the retina
Which of the photoreceptors are sensitive to light and dark only and functions best in low light intensities?
The rods
Which of the photoreceptors are sensitive to color and function best in high light intensities?
The cones
Where are the rods located?
These are located around the sides of the retina away from the fovea
Where are the cones located?
These are located mostly around the center of the retina.
What is the fovea?
This is the most sensitive part of the retina where most light rays are focused. It only contains cones.
What is the choroid?
This is the part of the eye that contains blood vessels which supply the retina with food and oxygen, and melanin to prevent the reflection of light inside the eye.
When does the pupil contract?
This occurs in bright lights to protect the eye from excess light
When does the pupil expand?
This occurs in dim light to take advantage of as much light as possible
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